OK, there is a bit of science to it but this is my understanding.
It depends on the load rating of the tyre and the weight at each corner.
The pressure numbers on the tyre placard usually depend on the load applied to the tyres and not so much the handling or comfort. It's a safety number to maintain the load rating.
On the side of the tyre there will be a load rating number and a speed rating letter.
For example on the side of a Kumho KU36 in 315/35/17 there is the number 102W
The load rating is 102 (850KG per tyre) and the max Speed rating W (270Km/h)
Most of the tyre manufacturers will publish the data for their tyres. Bob Jane has a handy table on their web page toi interpret the numbers.
load-index-speed-symbol
The load rating is a maximum load but it is dependent on pressure. So to know the pressure you need to run will depend on how much load you have on your tyre.
For example on the rear I have the 315/35/17 tyres. And say my car weighs 1100KG and has a 52% rear bias so that means 572KG on the rear wheels or 286KG per tyre.
I haven't been able to find the load tables for Kumho but Toyo have them on their site
LoadInflation_Table
If you go to the 2nd to last page it has the standard load inflation tables.
For 102 rated tyre at 36PSI the rating is 1874 pounds (850KG)
At 22 PSI the load is 1246 pounds or 565 KG. Still well above the actual load you are applying to the tyre.
So as long as you have enough pressure to maintain your load rating you can tune the pressures for comfort or cornering.
Hope this helps
Cheers
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